General information about migration to Python 3 - Revision history

Fourpointsix: Updated to reflect sunsetting of Python 2

2024-08-02T22:20:55Z

Updated to reflect sunsetting of Python 2

← Older revision		Revision as of 22:20, 2 August 2024
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	== Overview ==		== Overview ==
	Python 3 was released ~~9 years ago~~ and ~~EOL for~~ Python 2.7 ~~is scheduled for~~ 2020. Currently more and more Python project are switching to Python 3 or 2/3 compatible code. The issue of migrating Kodi’s built-in Python interpreter to Python 3.x was brought up on the Kodi forum several times. Now, thanks to a successful [[Archive:Google Summer of Code/2017\|Google Summer of Code 2017 project]], ~~we have a working Python 3 interpreter for~~ Kodi. ~~That is why on Kodi DevCon 2017 Team Kodi decided that we will switch~~ to Python 3 ~~in the future Kodi release (v.19 preliminarily)~~.		Python 3 was first released in 2008, and the last release of Python 2.7 was in 2020. Thanks to a successful [[Archive:Google Summer of Code/2017\|Google Summer of Code 2017 project]], Kodi 19.x (Matrix) became the first release to support Python 3.

	~~Unfortunately,~~ Python 3.x versions are not backward-compatible with Python 2.x, so we decided to urge addon developers to ~~start porting~~ their addons to Python 3 by making the addons compatible with both Python 2 and 3 and submitting them to the official repo. ~~This~~ way, when ~~Kodi with Python 3 is~~ released, we ~~won’t~~ have a situation ~~when we have~~ no working addons.		Since Python 3.x versions are not backward-compatible with Python 2.x, we decided to urge addon developers prior to the 19.x release to port their addons to Python 3 by making the addons compatible with both Python 2 and 3 and submitting them to the official repo. That way, when 19.x was to be released we wouldn't have a situation with no working addons. Looking back, the transition was rather successful.

			Over seven years have since passed and the last release supporting Python 2, 18.x (Leia), has aged out of support. As a result, Python 3 is the only supported addon environment.

			This article is for any addon developers who have not yet ported their old addons from Python 2.

	== The Process ==		== The Process ==
	* For Kodi 18 (~~Leia~~), only addons that are compatible with ~~both~~ Python ~~2 and~~ 3 will be accepted to the official addon repository.		* For Kodi 19.x (Matrix) and up, only addons that are compatible with Python 3 will be accepted to the official addon repository.
	* ~~We will provide Kodi 18 builds with Python 3 so that addon developers can tests if their addons are really compatible with Python 3.~~		* There's a thread on the Kodi forum so that addon devs can get help with their migration process.
	* A thread ~~will be created~~ on the Kodi forum so that addon devs can get help with their migration process.
	* Starting from Kodi 19 (Matrix), only Python 3 will be offered (and therefore only addons that are compatible with Python 3 will be accepted to the official addon repository).

	== Python 2 And 3 Differences ==		== Python 2 And 3 Differences ==
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	=== Potential pitfalls ===		=== Potential pitfalls ===
	When writing Python 2/3-compatible code or converting existing Python 2 codebase to compatible code you should pay attention to the following Python language constructions where TypeError exceptions may happen because of incompatible string types if you don’t get your strings in order:		When writing Python 3-compatible code or converting existing Python 2 codebase to compatible code you should pay attention to the following Python language constructions where TypeError exceptions may happen because of incompatible string types if you don’t get your strings in order:

	* String concatenations with + operator (<code>'foo' + 'bar'</code>).		* String concatenations with + operator (<code>'foo' + 'bar'</code>).

RogueScholar: /* Unicode strings by default */ Add link to orphaned page and clean up formatting

2022-03-19T18:34:39Z

Unicode strings by default: Add link to orphaned page and clean up formatting

← Older revision		Revision as of 18:34, 19 March 2022
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	=== Unicode strings by default ===		=== Unicode strings by default ===
	In Python 2 built-in <~~code~~>str</~~code~~> type holds the sequence of bytes so it can be used to store both binary data and textual data in ASCII or any of 8-bit fixed-length encodings ~~(there were plenty)~~. Python 2 also has <~~code~~>unicode</~~code~~> type that can store text in various writing systems. ~~A minimal~~ unit of a <~~code~~>unicode</~~code~~> object is a Unicode codepoint (a ~~Unicode~~ character). Both <~~code~~>str</~~code~~> and <~~code~~>unicode</~~code~~> objects can be mixed and matched together~~, for example,~~ concatenated using <code>+</code> operator.		:{{See also\|Unicode Concerns}}
			In Python 2, the built-in '''<tt>str</tt>''' type holds the sequence of bytes so it can be used to store both binary data and textual data in ASCII or any of a long list of 8-bit fixed-length encodings. Python 2 also has the '''<tt>unicode</tt>''' type that can store text in various writing systems. The fundamental atomic unit of a <tt>unicode</tt> object is a Unicode codepoint (a writing system character). Both <tt>str</tt> and <tt>unicode</tt> objects can be mixed and matched together (e.g. concatenated using the <code>+</code> operator).

	In Python 3 <~~code~~>str</~~code~~> type holds Unicode characters, and for binary data a new <~~code~~>bytes</~~code~~> type was added. This type was also added to Python 2.7 to simplify porting to Python 3 but in Python 2.7 bytes is simply an alias for <~~code~~>str</~~code~~>. The <~~code~~>str</~~code~~> and <~~code~~>bytes</~~code~~> types are incompatible, and an attempt to use both together will result in <~~code~~>TypeError</~~code~~> exception. A <~~code~~>bytes</~~code~~> object can be converted to <~~code~~>str</code> ~~using~~ .decode() method, and a <~~code~~>str</~~code~~> is converted to <~~code~~>bytes</code> ~~using~~ .encode() method.		In Python 3, the '''<tt>str</tt>''' type holds Unicode characters, and for binary data a new '''<tt>bytes</tt>''' type was added. This type was also added to Python 2.7 to simplify porting to Python 3, but in Python 2.7 <tt>bytes</tt> is simply an alias for <tt>str</tt>. The <tt>str</tt> and <tt>bytes</tt> types are incompatible, and an attempt to use both together will result in a <tt>TypeError</tt> exception. A <tt>bytes</tt> object can be converted to a <tt>str</tt> using the <code>.decode()</code> method, and conversely a <tt>str</tt> object is converted to <tt>bytes</tt> using the <code>.encode()</code> method.

	=== Absolute Import ===		=== Absolute Import ===

RogueScholar: Wikify mention of GSoC17 project and replace tags with

2021-09-13T02:04:08Z

Wikify mention of GSoC17 project and replace <source> tags with <syntaxhighlight>

Show changes

Karellen at 21:39, 16 December 2020

2020-12-16T21:39:47Z

← Older revision		Revision as of 21:39, 16 December 2020
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	[[Category:Python]]		[[Category:Python]]
			[[Category:Development]]

Karellen at 21:37, 16 December 2020

2020-12-16T21:37:59Z

← Older revision		Revision as of 21:37, 16 December 2020
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	* Kodi test builds with Python 3 for Linux Ubuntu: https://launchpad.net/~wsnipex/+archive/ubuntu/kodi-python3/+packages		* Kodi test builds with Python 3 for Linux Ubuntu: https://launchpad.net/~wsnipex/+archive/ubuntu/kodi-python3/+packages
	* “Python 3 migration” section on the Kodi official forum: https://forum.kodi.tv/forumdisplay.php?fid=281		* “Python 3 migration” section on the Kodi official forum: https://forum.kodi.tv/forumdisplay.php?fid=281


			[[Category:Python]]

Yol: Update to final migration plan

2019-10-27T15:41:21Z

Update to final migration plan

← Older revision		Revision as of 15:41, 27 October 2019
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	== The Process ==		== The Process ==

	* ~~Starting from~~ Kodi 18 (Leia), only addons that are compatible with both Python 2 and 3 will be accepted to the official addon repository.		* For Kodi 18 (Leia), only addons that are compatible with both Python 2 and 3 will be accepted to the official addon repository.
	* We will provide Kodi builds with Python 3 so that addon developers can tests if their addons are really compatible with Python 3.		* We will provide Kodi 18 builds with Python 3 so that addon developers can tests if their addons are really compatible with Python 3.
	* A thread will be created on the Kodi forum so that addon devs can get help with their migration process.		* A thread will be created on the Kodi forum so that addon devs can get help with their migration process.
			* Starting from Kodi 19 (Matrix), only Python 3 will be offered (and therefore only addons that are compatible with Python 3 will be accepted to the official addon repository).

	== Python 3 And 2 Differences ==		== Python 3 And 2 Differences ==

Roman V M: /* Absolute Import */

2018-02-12T12:56:23Z

Absolute Import

← Older revision		Revision as of 12:56, 12 February 2018
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	=== Absolute Import ===		=== Absolute Import ===
	Python 3 uses so called “absolute import” and you can no longer import modules from inside a package using only a module name. You need to either to use either a fully qualified name or a “dotted” notation.		Python 3 uses so called “absolute import” and you can no longer import neighbor modules from inside a package using only a module name. You need to either to use either a fully qualified name or a “dotted” notation.

	Let’s assume that you have a <code>foo</code> package that contains <code>bar</code> and <code>spam</code> modules:		Let’s assume that you have a <code>foo</code> package that contains <code>bar</code> and <code>spam</code> modules:

Roman V M: /* Absolute Import */

2018-02-04T13:57:34Z

Absolute Import

← Older revision		Revision as of 13:57, 4 February 2018
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	Python 3 uses so called “absolute import” and you can no longer import modules from inside a package using only a module name. You need to either to use either a fully qualified name or a “dotted” notation.		Python 3 uses so called “absolute import” and you can no longer import modules from inside a package using only a module name. You need to either to use either a fully qualified name or a “dotted” notation.

	Let’s assume that you have a foo package that contains bar and spam modules~~, and~~ you need to import bar module from spam. In Python 2 you can do:		Let’s assume that you have a <code>foo</code> package that contains <code>bar</code> and <code>spam</code> modules:
			<pre>
			foo/
			__init__.py
			bar.py
			spam.py
			</pre>
			And you need to import <code>bar</code> module from <code>spam</code>. In Python 2 you can do:
	<source lang="python">		<source lang="python">
	import bar		import bar

Roman V M: /* Potential pitfalls */

2018-01-19T11:55:41Z

Potential pitfalls

← Older revision		Revision as of 11:55, 19 January 2018
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	return s		return s
	</source>		</source>

			Those utility functions are included in Kodi Six library that is described in the following section.

	== Helper Libraries and Tools ==		== Helper Libraries and Tools ==

Roman V M: /* Helper Libraries and Tools */

2018-01-19T11:54:32Z

Helper Libraries and Tools

@@ Line 178: / Line 178: @@
 Future library also includes <code>futurize</code> command-line utility for converting existing Python 2 code to 2/3-compatible and in my experiments this utility showed good results.
 Future library (without additional utilities) is included in the Kodi addon repository as script.module.future addon.
 === PyCharm ===